Tips on removing plug insulator pieces from cylinder?

Shortly after I got a car tuned up it started missing. They found out that a fairly good-sized chunk of the plug's ceramic insulator had fallen off. I asked them about damage but they sait it would have instantly shattered into dust and been blown out the exhaust. Now that you've posted about using the boroscope, I wonder if I didn't have a chunk of ceramic bouncing around in the cylinder for a while after that.

On the plus side, maybe it's a good thing, to create turbulence and mix the fuel and air better, like the marble inside a spray paint can mixes the pigment with the solevent. Sorry, I was kidding there.

Ok, would it be feasable to idle the engine for a few minutes without a plug in that cylinder? It's almost certain to bounce that piece right out of the plug hole, unless it's at a sharp angle.

I had a NGK plug sitting in a cylinder that had a miss. I ended up doing much of what you are doing to correct it. The plug's insulator actually slid down the center conductor and touched the fingered (bent) adjustable contact of the plug when held in the "insulator down" position.

When I viewed the plug with the "insulator up" as one normally does when inspecting the plug, the insulator would slide back down into the plug as though it were a normal plug. Just when it goes into the engine (down pointing) did it cause the engine miss.

That was a fun plug! I suspect it cracked when they crimped the shell of the plug to seal it.

B~

I've caught a couple of Nippon Denso plugs with that issue. Just like you said, it can be hard to spot if the insulator slides back into position during inspection.

Toyota MDT in MO